COVID-19: Spread, prevention and risks
On this page
- How COVID-19 spreads
- Preventing COVID-19
- Risks of getting COVID-19
- Who is most at risk
- Recommendations for travellers
How COVID-19 spreads
COVID-19 can spread in different ways. Most of the time, it spreads when people are in close contact with others who are infected with the virus. You can transmit COVID-19 even before showing symptoms or without developing symptoms.
An infected person releases infectious respiratory particles into the air when they:
- breathe
- talk
- cough
- sneeze
- sing
- shout
These particles can land on another person, the ground or onto nearby surfaces. They may also linger in the air, especially in poorly ventilated indoor spaces.
You may become infected if:
- you breathe in infectious particles
- infectious particles come into contact with your eyes, nose or mouth
- for example, if someone who is infected:
- coughs or sneezes on you
- kisses or shares food or drinks with you
- for example, if someone who is infected:
- you touch your eyes, nose or mouth before you clean your hands after touching:
- someone who has infectious particles or secretions on them
- for example, when shaking someone's hand
- something that has infectious particles or secretions on it
- for example, touching contaminated surfaces or objects
- someone who has infectious particles or secretions on them
Contact with contaminated surfaces or objects
You may become infected if you touch a contaminated surface or object, and then touch your eyes, nose or mouth before you clean your hands.
High-touch surfaces and objects are more likely to be contaminated, including:
- phones
- door handles
- light switches
- elevator buttons
Studies show that the virus can stay active on surfaces and objects from a few hours to days, depending on the type of surface and environment.
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Animals
Based on available information to date, animal-to-human transmission is very uncommon.
People with COVID-19 can spread the virus to animals during close contact. To prevent possible infection, anyone with suspected or confirmed COVID-19 should avoid contact with:
- household pets
- other animals, including feeding wildlife
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Food
There's currently no evidence to suggest that food is a source of COVID-19. There haven't been any confirmed cases of COVID-19 being spread through food or food packaging.
Follow safe food handling advice to help reduce your risk of foodborne illnesses.
Learn more:
- Food safety
- Hand sanitizers approved by Health Canada
- Clean your hands to help reduce the spread of infectious diseases
Preventing COVID-19
Vaccination is one of the most important ways to protect yourself from developing serious complications from COVID-19. It's important to stay up to date with your vaccinations. Evidence shows that the COVID-19 vaccines used in Canada are very effective at preventing severe illness, hospitalization and death from COVID-19.
In addition to vaccination, use personal protective measures to help protect yourself and others.
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Personal protective measures
Personal protective measures are effective actions you can use every day to help reduce the risk of getting or spreading COVID-19. It's best to use multiple personal protective measures at the same time.
- Stay home and limit contact with others when you're sick, even if your symptoms are mild.
- Wear a well-constructed, well-fitting mask when appropriate.
- Improve indoor ventilation when possible.
- For example, by opening windows or doors if weather permits and it's safe to do so.
- Practising hand hygiene by:
- washing your hands regularly with soap and water for at least 20 seconds or
- using a hand sanitizer containing at least 60% alcohol
- Cover your coughs and sneezes with a tissue or your elbow.
- Clean and disinfect high-touch surfaces and objects.
Stay informed about COVID-19 disease activity in your area. Think about your risks and make informed decisions on using personal protective measures to keep yourself and others safe.
Learn more:
- My COVID-19 Visit Risk (calculator and decision aid)
- COVID-19: What to do if you or someone in your home is sick
- Clean your hands to help reduce the spread of infectious diseases
- Respiratory infectious diseases: How to reduce the spread with personal protective measures
Risks of getting COVID-19
COVID-19 will continue to spread at different levels in our communities, and outbreaks will still occur. New variants of concern may also emerge.
There's also uncertainty around how long immunity from vaccination and previous infection lasts.
We know that COVID-19 is most frequently transmitted when people are in close contact with others who are infected with the virus, especially when indoors. The risk is higher if people are also singing, shouting or breathing heavily (like when exercising) in these settings.
Some settings will be higher risk, including those that:
- are small
- are crowded
- have poor ventilation
- have people visiting for longer periods of time
Some high-risk settings may have measures in place to help prevent the spread of illness. Recommendations may vary for different public settings. Always follow the measures that a specific setting has put in place.
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Who is most at risk
You may be at risk of more severe disease or outcomes from COVID-19 if you:
- haven't received all of your recommended COVID-19 vaccine doses
- are an older person (risk increases progressively with age in older adults)
- have a chronic medical condition, including:
- if you're immunocompromised because:
- of an underlying medical condition, such as cancer or HIV
- you take medications that reduce the immune response, such as chemotherapy or corticosteroids
- you've had a solid organ or blood stem cell transplant
- asthma (moderate to severe)
- dementia
- diabetes
- heart disease
- high blood pressure
- kidney disease
- liver disease
- lung disease
- stroke
- if you're immunocompromised because:
- live with obesity (if you have a body mass index [BMI] of 40 or more)
- are pregnant
- have Down syndrome
If you're at higher risk, it's even more important that you reduce your risk of getting the virus. This means you should receive recommended vaccines and use personal protective measures in higher-risk settings.
Learn more:
- COVID-19: Pregnancy, childbirth and caring for a newborn
- COVID-19: What to do if you're at risk of more severe disease or outcomes (printable poster)
Recommendations for travellers
Don't travel if you're sick with COVID-19-like symptoms.
In general, it's important to talk to a health care provider or visit a travel health clinic preferably about 6 weeks before your trip to get personalized health advice. Even if your travel date is coming up soon, it's still worthwhile to make an appointment.
Review the travel advice and advisories page for your destination. The 'Health' section has information on the health risks at your destination and the steps you can take to reduce those risks.
Travel advice and advisories by destination
While abroad, protect your health and the health of others by:
- limiting contact with others if you become sick
- wearing a well-constructed and well-fitting mask, especially if you're:
- sick
- in a crowded or closed space (for example, airports, train stations or indoor events)
- cleaning your hands regularly by washing with soap and water for at least 20 seconds or using a hand sanitizer containing at least 60% alcohol
- covering your coughs and sneezes with a tissue or your elbow, not your hands
Learn more:
- Travel health notices
- Tips for healthy travel
- Symptoms of COVID-19
- Travel advice and advisories
- Clean your hands to help reduce the spread of infectious diseases
- Respiratory infectious diseases: Mask use for reducing the spread
Related links
- EI sickness benefits
- COVID-19: Proof of vaccination
- Post COVID-19 condition, long COVID
- COVID-19 and Indigenous communities
- Public health measures: Videos, factsheets and infographics (multilingual products available)
- COVID-19: Social media and promotional resources for Health Canada and Public Health Agency of Canada
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